背景:Swi6在出芽酵母中充当转录因子,在两种不同的异二聚体复合物中发挥作用,SBF和MBF,激活不同但重叠的基因的表达。Swi6在整个细胞周期中经历与基因表达变化相关的核质定位的调节变化。这项研究调查了多个转运因子的核质转运如何影响特定的Swi6活性。
结果:在这里,我们表明输出蛋白Crm1对于Swi6核输出和活性很重要。假定的Crm1NES的丧失或Crm1活性的抑制导致核质Swi6定位的变化。Swi6中Crm1NES的改变导致MBF介导的基因表达降低,但不影响SBF报告者的表达,这表明Crm1输出Swi6调节Swi6转录激活活性的一个子集。最后,Swi6中推定的Crm1NES的改变导致细胞大于野生型,并且这种细胞大小的增加因Msn5的缺失而加剧。
结论:这些数据提供了证据,表明Swi6至少有两种不同的出口蛋白,Crm1和Msn5,它们各自与不同的核输出信号相互作用。我们确定了Swi6中Crm1的推定核输出信号,并观察到Crm1或Msn5的输出独立地影响Swi6调节的不同Swi6控制基因子集的表达。这些发现为Swi6转录激活活性的复杂调节以及核质穿梭在调节基因表达中的作用提供了新的见解。
BACKGROUND: Swi6 acts as a transcription factor in budding yeast, functioning in two different heterodimeric complexes, SBF and MBF, that activate the expression of distinct but overlapping sets of genes.
Swi6 undergoes regulated changes in nucleocytoplasmic localization throughout the cell cycle that correlate with changes in gene expression. This study investigates how nucleocytoplasmic transport by multiple transport factors may influence specific Swi6 activities.
RESULTS: Here we show that the exportin Crm1 is important for Swi6 nuclear export and activity. Loss of a putative Crm1 NES or inhibition of Crm1 activity results in changes in nucleocytoplasmic Swi6 localization. Alteration of the Crm1 NES in Swi6 results in decreased MBF-mediated gene expression, but does not affect SBF reporter expression, suggesting that export of
Swi6 by Crm1 regulates a subset of
Swi6 transcription activation activity. Finally, alteration of the putative Crm1 NES in
Swi6 results in cells that are larger than wild type, and this increase in cell size is exacerbated by deletion of Msn5.
CONCLUSIONS: These data provide evidence that Swi6 has at least two different exportins, Crm1 and Msn5, each of which interacts with a distinct nuclear export signal. We identify a putative nuclear export signal for Crm1 within Swi6, and observe that export by Crm1 or Msn5 independently influences
Swi6-regulated expression of a different subset of
Swi6-controlled genes. These findings provide new insights into the complex regulation of Swi6 transcription activation activity and the role of nucleocytoplasmic shuttling in regulated gene expression.